The specific expression of prostate-specific membrane antigen (PSMA) makes it an ideal target for the diagnosis and treatment of prostate cancer. Currently, many 99mTc-labeled PSMA-targeted tracers have been developed. However, the high renal uptake of these 99mTc-labeled tracers is a common problem that limits their clinical application. In this work, the ligand (EUKPG) using DPro-Gly as the linker was synthesized and three 99mTc-labeled complexes ([99mTc]Tc-EUKPG-EDDA, [99mTc]Tc-EUKPG-TPPTS, [99mTc]Tc-EUKPG-TPPMS) with different coligands were prepared and evaluated. Among them, [99mTc]Tc-EUKPG-EDDA showed the most favorable pharmacokinetic properties, with significantly reduced uptake in the kidney (14.04 ± 0.23% ID/g), rapid clearance and low uptake in nontarget organs, thus making it to exhibit high tumor-to-background ratios (tumor/blood: 7.47, tumor/muscle: 12.65). Affinity studies have shown that it has high specificity for PSMA both in vivo and in vitro. Therefore, [99mTc]Tc-EUKPG-EDDA has great potential as a promising molecular tracer to target PSMA for tumor imaging.
In the field of nanotechnology, DNA-based nanoscale materials have facilitated the construction of DNA polyhedrons with different shapes and sizes by using predictable base pairing and highly tunable conformation. In this study DNA bipyramid nanostructures with one arm chain (T20-DBNs) were successfully prepared in a single annealing procedure. 99m Tc-A20 ssDNA was obtained by radiolabeled DTPA-A20 with 99m Tc, and then 99m Tc-DTPA-DBNs were obtained by hybridizing T20-DBNs with 99m Tc-A20 ssDNA. We focused on studying a method of 99m Tc radiolabeling DNA nanostructures with DTPA as a chelate, and hoped to develop a new SPECT molecular imaging probe based on DNA nanostructures.
Idiopathic pulmonary fibrosis (IPF) is a progressive fibrotic disease with poor prognosis. Evidence has shown that vimentin is a key regulator of lung fibrogenesis. 99mTc-labeled N-acetylglucosamine-polyethyleneimine (NAG-PEI), a vimentin-targeting radiotracer, was used for the early diagnosis of IPF, and NAG-PEI was also used as a therapeutic small interfering RNA (siRNA) delivery vector for the treatment of IPF in this study. Single-photon emission-computed tomography (SPECT) imaging of bleomycin (BM)- and silica-induced IPF mice with 99mTc-labeled NAG-PEI was performed to visualize pulmonary fibrosis and monitor the treatment efficiency of siRNA-loaded NAG-PEI, lipopolysaccharide (LPS, a tolerogenic adjuvant), or zymosan (ZYM, an immunostimulant). The lung uptakes of 99mTc-NAG-PEI in the BM- and silica-induced IPF mice were clearly and directly correlated with IPF progression. The lung uptake of 99mTc-NAG-PEI in the NAG-PEI/TGF-β1-siRNA treatment group or LPS treatment group was evidently lower than that in the control group, while the lung uptake of 99mTc-NAG-PEI was significantly higher in the ZYM treatment group compared to that in the control group. These results demonstrate that NAG-PEI is a potent MicroSPECT imaging-guided theranostic platform for IPF diagnosis and therapy.
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